A lubricant with a polyacrylate based on c13/15 acrylate

ABSTRACT

The present invention relates to a lubricant comprising a polyacrylate which contains a C 13/15  acrylate in polymerized form, where the C 13/15  acrylate comprises at least 70 wt % of linear and branched C 13  and C 15  alkyl (meth)acrylates. It further relates to the polyacrylate, to the C 13/15  acrylate, to a method for preparing the polyacrylate by free-radical polymerization of the C 13/15  acrylate, and to a method for preparing a lubricant by contacting the polyacrylate to a base oil.

The present invention relates to a lubricant comprising a polyacrylate which contains a C_(13/15) acrylate in polymerized form, where the C_(13/15) acrylate comprises at least 70 wt % of linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates. It further relates to the polyacrylate, to the C_(13/15) acrylate, to a method for preparing the polyacrylate by free-radical polymerization of the C_(13/15) acrylate, and to a method for preparing a lubricant by contacting the polyacrylate to a base oil. Combinations of preferred embodiments with other preferred embodiments are within the scope of the present invention.

Lubricants comprising poly(alkyl)(meth)acrylates are known, yet they need still improvement.

The object was solved by a lubricant comprising a polyacrylate which contains a C_(13/15) acrylate in polymerized form, where the C_(13/15) acrylate comprises at least 70 wt % of linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates. The object was also solved by the polyacrylate. The object was also solved by the C_(13/15) acrylate. The object was also solved by a method for preparing the polyacrylate by free-radical polymerization of the C_(13/15) acrylate. The object was also solved by a method for preparing a lubricant by contacting the polyacrylate to a base oil.

The C_(13/15) acrylate is usually a technical mixture of alkyl (meth)acrylates. The C_(13/15) acrylate is usually a monomer in a technical grade, which typically contains a technical mixture of alkyl (meth)acrylates, e.g. C₁₂-C₁₆ alkyl(meth)acrylates. Technical grade monomers are commercially available in large scale, such as those named in the comparative examples of this application.

In another form the C_(13/15) acrylate is a technical mixture of alkyl (meth)acrylates in the form of a commercially available monomer.

The C_(13/15) acrylate comprises at least 70 wt %, such as at least 75, 80, 85, 90, 95, 97 or 99 wt % of linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates. Usually, the C_(13/15) acrylate comprises at least four different linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates.

The wt % of the various alkyl (meth)acrylates in the C_(13/15) acrylate is usually determined by the GC analysis of the C_(13/15) alcohol, which were used for preparation of the C_(13/15) acrylate. The area % of the GC usually correspond to wt %.

The wt % of the various alkyl (meth)acrylates in the C_(13/15) acrylate usually relates to the whole technical mixture of the alkyl (meth)acrylates (e.g. the C₁₂-C₁₆ alkyl(meth)acrylates) in the C_(13/15) acrylate. For example, 100 g of a Monomer X in a technical grade may consist of a mixture of C₁₂-C₁₆ alkyl(meth)acrylates, wherein 80 g are linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates, 10 g are C₁₂ alkyl(meth)acrylates, 10 g are C₁₄ alkyl(meth)acrylates, and traces of C₁₆ alkyl(meth)acrylates. This would correspond roughly to 80 wt % of of linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates, 10 wt % of C₁₂ alkyl(meth)acrylates, 10 wt % of C₁₄ alkyl(meth)acrylates, and wt % traces of C₁₆ alkyl(meth)acrylates.

The term “(meth)acrylate” may refer to acrylate and/or methacrylate, where the latter is preferred. The linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates preferably comprise C₁₃ and C₁₅ alkyl methacrylates. The linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates usually refers to a mixture of different alkyl (meth)acrylates, where the alkyl groups are a mixture of linear and branched tridecyl and linear and branched pentadecyl.

A linear C₁₃ alkyl (meth)acrylate can also be called a n-tridecyl (meth)acrylate. A linear C₁₅ alkyl (meth)acrylate can also be called a n-pentadecyl (meth)acrylate.

Any type of branched C₁₃ and C₁₅ alkyl (meth)acrylates are possible, such as 2-methyl branched, 2-ethyl branched or higher branched C₁₃ and C₁₅ alkyl (meth)acrylates. The term higher branched alkyl may summarize alkyl which has C₃ and longer alkyl branches at the 2 position, alkyl which a branch at a position other than the 2 position, and alkyl with more than one branch. Prefered are 2-methyl branched and 2-ethyl branched C₁₃ and C₁₅ alkyl (meth)acrylates.

The C_(13/15) acrylate may comprise

20 to 60 wt % of linear C₁₃ alkyl groups,

10 to 50 wt % of branched C₁₃ alkyl groups,

3 to 30 wt % of linear C₁₅ alkyl groups, and

3 to 30 wt % of branched C₁₅ alkyl groups.

In another form the C_(13/15) acrylate may comprise

25 to 55 wt % of linear C₁₃ alkyl groups,

15 to 45 wt % of branched C₁₃ alkyl groups,

5 to 25 wt % of linear C₁₅ alkyl groups, and

5 to 25 wt % of branched C₁₅ alkyl groups.

In another form the C_(13/15) acrylate may comprise

30 to 50 wt % of linear C₁₃ alkyl groups,

20 to 40 wt % of branched C₁₃ alkyl groups,

10 to 20 wt % of linear C₁₅ alkyl groups, and

10 to 20 wt % of branched C₁₅ alkyl groups.

In another form the C_(13/15) acrylate may comprise

25 to 40 wt % of linear C₁₃ alkyl groups,

30 to 50 wt % of branched C₁₃ alkyl groups,

10 to 20 wt % of linear C₁₅ alkyl groups, and

10 to 25 wt % of branched C₁₅ alkyl groups.

The C_(13/15) acrylate may comprise at least 20, 25, 30, 35, 40, or 50 wt % of branched C₁₃ and C₁₅ alkyl groups. The C_(13/15) acrylate may comprise up to 80, 70, 60, 55, or 50 wt % of branched C₁₃ and C₁₅ alkyl groups. The C_(13/15) acrylate may comprise 20 to 70 wt %, preferably 30 to 60 wt %, and in particular 40 to 50 wt % of branched C₁₃ and C₁₅ alkyl groups. In another form the C_(13/15) acrylate may comprise 30 to 70 wt %, preferably 40 to 70 wt %, and in particular 50 to 60 wt % of branched C₁₃ and C₁₅ alkyl groups.

The C_(13/15) acrylate may comprise at least 5, 10, 15, 20, 25, 30 or 35 wt % of branched C₁₃ alkyl groups. The C_(13/15) acrylate may comprise up to 60, 50, 40, 35, or 30 wt % of branched C₁₃ alkyl groups. The C_(13/15) acrylate may comprise 5 to 60 wt %, preferably 15 to 50 wt %, and in particular 20 to 40 wt % of branched C₁₃ alkyl groups. In another form the C_(13/15) acrylate may comprise 20 to 60 wt %, preferably 25 to 50 wt %, and in particular 30 to 50 wt % of branched C₁₃ alkyl groups.

The C_(13/15) acrylate may comprise at least 5, 10, or 15 wt % of branched C₁₅ alkyl groups. The C_(13/15) acrylate may comprise up to 40, 30 or 20 wt % of branched C₁₅ alkyl groups. The C_(13/15) acrylate may comprise 5 to 50 wt %, preferably 5 to 40 wt %, and in particular 10 to 30 wt % of branched C₁₅ alkyl groups.

The C_(13/15) acrylate may comprise at least 20, 30, 40, 50, 55, or 60 wt % of linear and branched C₁₃ alkyl groups. The C_(13/15) acrylate may comprise up to 90, 85, 80, 75, or 70 wt % of linear and branched C₁₃ alkyl groups. The C_(13/15) acrylate may comprise 35 to 85 wt %, preferably 45 to 80 wt %, and in particular 55 to 75 wt % of linear and branched C₁₃ alkyl groups.

The C_(13/15) acrylate may comprise at least 10, 15, 20, 25, or 30 wt % of linear and branched C₁₅ alkyl groups. The C_(13/15) acrylate may comprise up to 60, 50, or 40 wt % of linear and branched C₁₅ alkyl groups. The C_(13/15) acrylate may comprise 10 to 60 wt %, preferably 20 to 50 wt %, and in particular 25 to 40 wt % of linear and branched C₁₅ alkyl groups.

The C_(13/15) acrylate may comprise a weight ratio of C₁₃ alkyl to C₁₅ alkyl in a range from 90:10 to 30:70, 90:10 to 40:60, 80:20 to 50:50, or 75:25 to 60:40. Preferably, the C_(13/15) acrylate may comprise a weight ratio of C₁₃ alkyl to C₁₅ alkyl in a range from 90:10 to 40:60, and in particular 80:20 to 50:50.

The C_(13/15) acrylate may comprise a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 5:1 to 1:5, 3:1 to 1:3, 2:1 to 1:2, or 1.5:1 to 1:1.5.

In a preferred form the C_(13/15) acrylate may comprise a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 1:1.05 to 1:3, 1:1.10 to 1:3, 1:1.15 to 1:2.5, or 1:1.20 to 1:2. Preferably, the C_(13/15) acrylate may comprise a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 1:1.1 to 1:3, and in particular from 1:1.15 to 1:2.5.

In another preferred form the C_(13/15) acrylate may comprise a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 1.05:1 to 3:1, 1.1:1 to 3:1, 1.15:1 to 2.5:1, or 1.2:1 to 2:1. Preferably, the C_(13/15) acrylate may comprise a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 1.1:1 to 3:1, and in particular from 1.15:1 to 2.5:1.

The C_(13/15) acrylate may comprise other alkyl (meth)acrylates in addition to the linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates, such as C₁₂, C₁₄ and C₁₆ alkyl(meth)acrylates. The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of other alkyl (meth)acrylates in addition to the linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates. The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of each C₁₂, C₁₄ and C₁₆ alkyl (meth)acrylate. The C_(13/15) acrylate may preferably comprise less than 5 wt %, and in particular less than 1 wt % of each C₁₂, C₁₄ and C₁₆ alkyl (meth)acrylate.

The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of C₁₂ alkyl (meth)acrylate. The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of C₁₄ alkyl (meth)acrylate. The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of C₁₆ alkyl (meth)acrylate. The C_(13/15) acrylate may comprise less than 10, 8, 6, 5, 4, 3, 2, 1, 0.5, 0.3 or 0.1 wt % of the sum of C₁₂, C₁₄ and C₁₆ alkyl (meth)acrylate.

The C_(13/15) acrylate may be prepared by reacting (meth)acrylic acid with an alcohol in the presence of at least one acidic catalyst, optionally in the presence of at least one polymerization inhibitor and optionally in the presence of a solvent. Suitable processes are described in WO 2011/064190.

Useful acidic catalysts include the mineral acids and sulfonic acids, preferably sulfuric acid, phosphoric acid, alkylsulfonic acids (e.g. methanesulfonic acid, trifluoromethanesulfonic acid) and arylsulfonic acids (e.g. benzene-, p-toluene-, or dodecylbenzenesulfonic acid) or mixtures thereof, but acidic ion exchangers or zeolites are also conceivable. Acidic catalysts are sulfuric acid, methanesulfonic acid and p-toluenesulfonic acid, or mixtures thereof.

Suitable polymerization inhibitors are at least one compound from the group of hydroquinone, hydroquinone monomethyl ether, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2 methyl-4-tert-butylphenol, hypophosphorous acid, copper acetate, copper(II) chloride, copper salicylate and cerium(III) acetate. Preference is given to phenothiazine and/or hydroquinone monomethyl ether (MEHQ) as the polymerization inhibitor.

Suitable solvents for azeotropic removal of the water of reaction are aliphatic, cycloaliphatic and aromatic hydrocarbons or mixtures thereof. Preference is given to n-pentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, benzene, toluene or xylene.

The C_(13/15) acrylate comprises the linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates, where the linear and branched C₁₃ and C₁₅ alkyl groups are derived from linear and branched C₁₃ and C₁₅ alkanols. The linear and branched C₁₃ and C₁₅ alkanols are usually a technical mixture of linear and branched tridecanols and linear and branched pentadecanols, and in the following also called C_(13/15) alkanols. The C_(13/15) alkanols are usually primary alcohols.

The C_(13/15) alkanols are typically obtainable by reacting a monoolefin mixture of C₁₂ and C₁₄ olefins with carbon monooxide and hydrogen, for example according to WO 2002/00580. Preferably, the linear and branched C₁₃ and C₁₅ alkyl groups of the C_(13/15) acrylate are derived from a C_(13/15) alkanol obtained by reacting a monoolefin mixture of C₁₂ and C₁₄ olefins with carbon monooxide and hydrogen.

The C_(13/15) alkanols may be prepared by a process where

a) a monoolefin mixture is prepared, substantively comprising olefins having 12 and 14 carbon atoms and having linear a-olefins and from 5 to 20% by weight of olefins other than these, and

b) the monoolefin mixture is hydroformylated by reaction with carbon monooxide and hydrogen in the presence of a rhodium catalyst, and is hydrogenated.

Step a)

The process preferably uses a monoolefin mixture produced on an industrial scale. Examples of these are the Ziegler olefins obtained by controlled oligomerization of ethene in the presence of alkylaluminum catalysts. They also include the olefins obtained by oligomerization of ethene in the presence of various catalyst systems, e.g. the olefins obtained in the presence of alkylaluminum chloride/titanium tetrachloride catalysts, or in the presence of nickel-phosphine complex catalysts using the Shell Higher Olefin Process (SHOP). Other suitable industrially accessible olefin mixtures are obtained in the paraffin-dehydrogenation of appropriate mineral oil fractions, e.g. of what are known as the petroleum or diesel oil fractions.

There are three processes of which substantive use is made for converting paraffins, mainly n-paraffins, into olefins: thermal cracking (steam-cracking), catalytic dehydrogenation, and chemical dehydrogenation via chlorination and dehydrochlorination. Thermal cracking here leads mainly to a-olefins, whereas the other techniques give olefin mixtures which generally include olefins having a non-terminal double bond. Other suitable olefin mixtures are the olefins obtained in metathesis reactions or telomerization reactions. Examples of these are the olefins from the Philipps triolefin process, a modified SHOP process comprising ethylene oligomerization, double-bond isomerization, and subsequent metathesis (etheneolysis). Other processes for preparing suitable olefins are the preparation of α,ω-diolefins by ring-opening etheneolysis of cycloolefins, the metathesis polymerization of cycloolefins to give polyalkeneamers with subsequent etheneolysis, etc. Etheneolysis generally gives a high concentration of n-α-olefins.

Industrially accessible monoolefin mixtures of olefins having 12 carbon atoms and olefins having 14 carbon atoms are also called C₁₂-C₁₄ olefins. Preference is given to mixtures in which the ratio of olefins having 12 carbon atoms to olefins having 14 carbon atoms is in the range from 90:10 to 50:50 by weight, preferably from 70:30 to 60:40 by weight. Particular preference is given to C₁₂-C₁₄ olefins in which the ratio of mixing of the olefins is in the region of about 2:1.

The process is advantageously suitable for preparing alcohol mixtures from industrially accessible monoolefin mixtures which generally comprise not only linear a-olefins but also olefins having non-terminal double bonds and branched olefins. The process is therefore more cost-effective than prior art processes which are dependent on the use of linear α-olefins, or in which olefins other than linear α-olefins are not converted into useful products. Suitable industrial monoolefin mixtures generally have up to 15% by weight of olefins other than α-olefins. These include not only olefins having non-terminal double bonds but also vinylidene-branched olefins which have a group of the formula (—C(R^(a))═CH₂), where R^(a) is alkyl, preferably C₁-C₆-alkyl, in particular methyl or ethyl. Examples of processes which give vinylidene-branched olefin isomers of this type are the dimerization of low-molecular-weight olefin cuts or the incorporation of higher n-1-olefins during ethene oligomerization in the Ziegler process.

The process preferably uses a monoolefin mixture which, based on the total olefin content, comprises from 85 to 95% by weight of linear α-olefins, from 1 to 5% by weight of linear non-terminal olefins, from 5 to 10% by weight of vinylidene-branched olefins, and, where appropriate, up to 5% by weight of other olefin isomers differing therefrom. These other olefin isomers include, for example, isomers which have more than one branching point, and isomers having a longer-chain vinylidene branch.

Step b)

The hydroformylation in step b) takes place under conditions in which it is not only the linear α-olefins which are hydroformylated but essentially all of the olefins in the monoolefin mixture used.

Suitalbe catalysts used for the hydroformylation in step b) derive usually from conventional rhodium complexes or salts known to the skilled worker, as usually used in hydroformylation reactions. The amount used of the rhodium catalysts is generally in the range from about 1 to 150 ppm, preferably from 1 to 100 ppm.

The ligands preferably used here enable the catalyst, under the reaction conditions, to catalyze both the hydroformylation of linear α-olefins and that of olefins having non-terminal double bonds and/or that of branched olefins. The catalyst used in step b) preferably has at least one ligand selected among compounds capable of forming complexes and having carbonyl, carboxylate, hydride, sulfate, or nitrate groups, or having nitrogen-containing and/or phosphorus-containing groups, where the phosphorus-containing group has no more than one aryl radical with single bonding to the phosphorus atom.

Suitable rhodium catalysts or rhodium catalyst precursors are rhodium(II) salts and rhodium(III) salts, such as rhodium(III) chloride, rhodium(III) nitrate, rhodium(III) sulfate, potassium rhodium sulfate (rhodium alum), rhodium(II) carboxylate, rhodium(III) carboxylate, preferably rhodium(II) acetate or rhodium(III) acetate, rhodium(II) ethylhexanoate or rhodium(III) ethylhexanoate, rhodium(III) oxide, salts of rhodium(III) acid, and trisammonium hexachlororhodate(III).

Other suitable rhodium catalysts are rhodium complexes of the formula RhX_(m)L¹L²(L³)_(n), where X is halide, preferably chloride, or bromide, alkyl carboxylate, aryl carboxylate, acetylacetonate, arylsulfonate or alkylsulfonate, in particular phenylsulfonate or toluenesulfonate, hydride or the diphenyltriazine anion, and L¹, L², and L³, independently of one another, are CO, olefins, cycloolefins, preferably cyclooctadiene (COD). X is preferably hydride, chloride, bromide, acetate, tosylate, acetylacetonate, or the diphenyltriazine anion, in particular hydride, chloride or acetate. Other suitable catalysts are listed in WO 2002/00580, page 7, line 11 to page 23, line 34 and the literature cited therein.

The reaction temperature is generally in the range from room temperature to 200° C., preferably from 50 to 180° C., in particular from 80 to 150° C. The reaction may be carried out at an elevated pressure from about 10 to 1000 bar, preferably from 20 to 650 bar, in particular from 80 to 350 bar.

The molar ratio H₂:CO is generally from about 1:5 to about 5:1, preferably from 1:2 to 2:1. The aldehydes or aldehyde/alcohol mixtures produced during the hydroformylation may, if desired, be isolated and, where appropriate, purified by methods known to the skilled worker prior to the hydrogenation process. It is preferable for the hydroformylation catalyst to be removed from the reaction mixture prior to the hydrogenation process. It can generally be reused for the hydroformylation process, where appropriate after treatment.

For the hydrogenation process the reaction mixtures obtained during the hydroformylation are reacted with hydrogen in the presence of a hydrogenation catalyst. Suitable hydrogenation catalysts are generally transition metals, e.g. Cu, Cr, Mo, W, Fe, Rh, Co, Ni, Pd, Pt, Ru, etc., or mixtures of these, and to increase activity and stability they may be applied to supports, e.g. activated carbon, aluminum oxide, silicon dioxide, kieselghur, etc. To increase catalytic activity it is also possible to use Fe, Co, and preferably Ni in the form of Raney catalysts as a spongiform metal with very high surface area. Preference is given to the use of heterogeneous catalysts which have become established in industry, for example active compositions on supports or unsupported catalysts, used, for example, by the up flow or down flow method, or in suspension. The pressure is preferably in the range from about 5 to 350 bar. It is preferable to use a slight molar excess of hydrogen. Use may also be made of other processes for the reduction of the aldehydes to give the alcohols. Examples of these are reduction using complex hydrides, e.g. LiAlIH₄or NaBH₄, Bouveault-Blanc reduction using sodium in ethanol, and also other known processes.

The polyacrylate contains the C_(13/15) acrylate in polymerized form. The polyacrylate can be prepared by free-radical polymerization of the C_(13/15) acrylate. Conventional methods of free-radical polymerization can be used to prepare the polyacrylate. Polymerization of the corresponding monomers can take place under a variety of conditions, including bulk polymerization, solution polymerization, usually in an organic solvent, preferably mineral oil.

In the solution polymerization, the reaction mixture comprises a diluent, the monomers to be polymerized, a polymerization initiator and usually a chain transfer agent and optionally a crosslinker.

The diluent may be any inert hydrocarbon. The concentration of total monomers may range from 30 to 90%. As used herein, “total monomer charge” means the combined amount of all monomers in the initial, i.e., unreacted, reaction mixture.

In preparing the polyacrylate by free-radical polymerization the monomers may be polymerized simultaneously or sequentially or the monomers may be fed over time to the reaction vessel.

Suitable polymerization initiators include initiators which disassociate upon heating to yield a free radical, e.g., peroxide compounds such as benzoyl peroxide, t-butyl perbenzoate, t-butyl peroctoate and cymene hydroperoxide; and azo compounds such as azo isobutyronitrile and 2,2′-azobis (2-methylbutanenitrile). The mixture includes from 0.001 wt.-% to 5.0 wt.-% initiator relative to the total monomer mixture. For example, 0.02 wt.-% to 4.0 wt.-%, 0.02 wt.-% to 3.5 wt.-% are envisioned. Typically 0.02 wt.-% to 2.0 wt.-% are used.

Suitable chain transfer agents include those conventional in the art such as mercaptanes and alcohols. For example, tridecyl mercaptane, dodecyl mercaptane and ethyl mercaptane, but also bifunctional mercaptanes, such hexane dithiol may be used as chain transfer agents. The selection of the amount of chain transfer agent to be used is based on the desired molecular weight of the polymer being synthesized as well as the desired level of shear stability for the polymer, i.e., if a more shear stable polymer is desired, more chain transfer agent can be added to the reaction mixture. The chain transfer agent is added to the reaction mixture or monomer feed in an amount of 0.001 to 3 wt.-% relative to the monomer mixture.

By way of example, all components are charged to a reaction vessel that is equipped with a stirrer, a thermometer and a reflux condenser and heated with stirring under a nitrogen blanket to a temperature from 50° C. to 125° C. for a period of 0.5 hours to 15 hours to carry out the polymerization reaction.

The molecular weight distribution measured by GPC analysis using polystyrene standards is preferably less than 5.0 and generally ranges from 2.0 to 4.5, preferably from 3.0 to 4.4, and more preferably from 3.1 to 4.3.

The molecular weight is determined by GPC using a poly methyl methacrylate standard. The determined average molecular weight is therefore relative to the standard not absolute.

The molecular weight M_(w) of the polyacrylate can be varied in broad ranges, such as from 1000 to 1,000,000 g/mol. The Mw is usually adapted to the application of the lubricant as listed below.

The polyacrylate may be a homopolymer or copolymer of the C_(13/15) acrylate. In a preferred form the polyacrylate is a homopolymer of the C_(13/15) acrylate. In another preferred form the polyacrylate is a copolymer of the C_(13/15) acrylate.

The polyacrylate may comprises at least 20, 30, 40, 50, 60, 70, 80, 90, or 95 wt % of the C_(13/15) acrylate. The polyacrylate comprises preferably at least 50 wt %, and in particular at least 70 wt % of the C_(13/15) acrylate.

The polyacrylate may comprise at least one type of comonomers in polymerized form in addition to the C_(13/15) acrylate.

The comonomer can be selected from a linear or branched C₁-C₃₄ alkyl (meth)acrylate, preferably C₁-C₁₈ alkyl (meth)acrylate, or in particular C₁-C₆ alkyl (meth)acrylate. Suitable C₁-C₃₄ alkyl (meth)acrylate have an alkyl chain selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2-propyl heptyl, nonyl, decyl, stearyl, lauryl, octadecyl, heptadecyl, nonadecyl, eicosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, hexacosyl, octacosyl, nonacosyl, triacontyl and behenyl.

The use of hydroxyl-, epoxy- and/or amino-functional (meth)acrylate monomers as well as other functionally modified (meth)acrylate monomers is also generally possible although pure alkyl acrylates which have no further functional groups like for instance hydroxyl-, epoxy-, and/or amino-functional groups or the like are more preferred as the comonomers.

The comonomer can be selected from dispersing monomer, such as aminoalkyl(meth)-acrylates, aminoalkyl(meth)acrylamides, hydroxylalkyl(meth)acrylates, heterocyclic(meth)acrylates and/or carbonyl-containing (meth)acrylates.

The hydroxyalkyl(meth)acrylates include, among others, 2-hydroxypropyl(meth)acrylate, 3,4-dihydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2,5-dimethyl-1,6-hexanediol(meth)acrylate, and 1,10-decanediol(meth)acrylate.

Carbonyl-containing (meth)acrylates comprise, for example, 2-carboxyethyl(meth)acrylate, carboxymethyl(meth)acrylate, N-(methacryloyloxy)formamide, acetonyl(meth)acrylate, Mono-2-(meth)acryloyloxyethyl succinate, N-(meth)acryloylmorpholine, N-(meth)acryloyl-2-pyrrolidinone, N-(2-(meth)acryloyloxyethyl)-2-pyrrolidinone, N-(3-(meth)acryloyloxypropyl)-2-pyrrolidinone, N-(2-(meth)acryloyloxypentadecyl)-2-pyrrolidinone, N-(3-(meth)acryloyloxyheptadecyl)-2-pyrrolidinone, and, N-(2-(meth)acryloyloxyethyl)ethylenurea, 2-acetoacetoxyethyl(meth)acrylate.

The heterocyclic(meth)acrylates include, among others, 2-(1-imidazolyl)ethyl(meth)acrylate, oxazolidinylethyl(meth)acrylate, 2-(4-morpholinyl)ethyl(meth)acrylate, 1-(2-methacryloyloxy-ethyl)-2-pyrrolidone, N-methacryloylmorpholine, N-methacryloyl-2-pyrrolidinone, N-(2-meth-acryloyloxyethyl)-2-pyrrolidinone, N-(3-methacryloyloxypropyl)-2-pyrrolidinone.

The aminoalkyl(meth)acrylates include more particularly, N,N-dimethylaminoethyl(meth)-acrylate, N,N-dimethylaminopropyl(meth)acrylate, N,N-diethylaminopentyl(meth)acrylate, N,N-dibutylaminohexadecyl(meth)acrylate.

Additionally it is possible to use aminoalkyl(meth)acrylamides as dispersing monomers, such as

N,N-dimethylaminopropyl(meth)acrylamide.

Furthermore, it is possible to use phosphorus-, boron- and/or silicon-containing (meth)acrylates as dispersing monomers, such as, 2-(dimethylphosphato)propyl(meth)acrylate, 2-(ethylene-phosphito)propyl(meth)acrylate, dimethylphosphinomethyl(meth)acrylate, dimethylphosphono-ethyl(meth)acrylate, diethyl(meth)acryloylphosphonate, dipropyl(meth)acryloylphosphate, 2-(d-ibutylphosphono)ethyl(meth)acrylate, 2,3-butylene(meth)acryloylethylborate, methyldiethoxy(meth)acryloylethoxysilane, diethylphosphatoethyl(meth)acrylate.

The preferred heterocyclic vinyl compounds include, among others, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole, N-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone, 2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran, vinylthiophene, vinylthiolane, vinylthiazoles and hydrogenated vinylthiazoles, and vinyloxazoles and hydrogenated vinyloxazoles.

The particularly preferred dispersing monomers include more particularly ethylenically unsaturated compounds which comprise at least one nitrogen atom, these compounds being selected with particular preference from the aforementioned heterocyclic vinyl compounds and/or aminoalkyl(meth)acrylates, aminoalkyl(meth)acrylamides and/or heterocyclic (meth)acrylates.

In a preferred form the comonomer is a dispersing monomer selected form DMAEMA (2-(dimethylamino)ethyl methacrylate), DMAPMA (3- dimethylaminopropyl methacrylamide), N-vinylpyrrolidon, and N-vinyl-imidazol.

The aforementioned ethylenically unsaturated monomers can be used individually or as mixtures. It is possible, furthermore, to vary the monomer composition during the polymerization of the main chain, in order to obtain defined structures, such as block copolymers or graft polymers, for example.

Further suitable comonomers are vinyl aromatic compounds, such as styrene, alpha-methyl styrene, vinyl toluene or p-(tert-butyl) styrene; vinyl acetate; acrylic and methacrylic acid; acrylamide and methacrylamide; maleic acid and the imides and C1 to C10-alkyl esters thereof; fumaric acid and the imides and C1 to C10-alkyl esters thereof; itaconic acid and the imides and C1 to C10-alkyl esters thereof; acrylonitrile and methacrylonitrile; macromonomers based on polyisobutylene, hydrogenated polybutadiene or end-functionalized polymethacrylates (e.g. made with RAFT technology).

Preferred comonomers are linear or branched C₁-C₃₄ alkyl (meth)acrylate, preferably C₁-C₁₈ alkyl (meth)acrylate, or in particular C₁-C₆ alkyl (meth)acrylate.

The comonomer may be present in the polyacrylate in an amount of from 1 to 40 wt %, more preferably from 10 to 35 wt %, even more preferably from 15 to 35 wt %, based on the total weight of the polyacrylate.

In a preferred form the polyacrylate comprises up to 50, 40, 30, 25, 20, 15, 10 or 5 wt % of a C₁-C₁₈ alkyl (meth)acrylate. In a preferred form the polyacrylate comprises up to 50, 40, 30, 25, 20, 15, 10 or 5 wt % of a C₁-C₆ alkyl (meth)acrylate.

Lubricants usually refers to composition which are capable of reducing friction between surfaces (preferably metal surfaces), such as surfaces of mechanical devices. A mechanical device may be a mechanism consisting of a device that works on mechanical principles. Suitable mechanical device are bearings, gears, joints and guidances. The mechanical device may be operated at temperatures in the range of −30 C to 80° C. Lubricants are usually specifically formulated for virtually every type of machine and manufacturing process. The type and concentration of base oils and/or lubricant additives used for these lubricants may be selected based on the requirements of the machinery or process being lubricated, the quality required by the builders and the users of the machinery, and the government regulation. Typically, each lubricant has a unique set of performance requirements. In addition to proper lubrication of the machine or process, these requirements may include maintenance of the quality of the lubricant itself, as well as the effect of the lubricant's use and disposal on energy use, the quality of the environment, and on the health of the user. The lubricant is usually a lubricating liquid, lubricating oil or lubricating grease.

Typical lubricants are automotive lubricants (e.g. gasoline engine oils, diesel engine oils, gas engine oils, gas turbine oils, automatic transmission fluids ATF, manual transmission fluid MTF, continuously variable transmission fluid CVTF, gear oils) and industrial lubricants (e.g. industrial gear oils, pneumatic tool lubricating oil, high temperature oil, gas compressor oil, hydraulic fluids, metalworking fluids).

Examples for lubricants are axel lubrication, medium and heavy duty engine oils, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hydrocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation turbine oils, transmission oils, gas turbine oils, spindle oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insulating oils, instrument oils, brake fluids, transmission liquids, shock absorber oils, heat distribution medium oils, transformer oils, fats, chain oils, minimum quantity lubricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, drilling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, molding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants.

The concentration of the polyacrylate in the lubricant (also called treat rate) can be varied in broad ranges, such as from 0.1 to 100 wt %, or from 0.5 to 90 wt %. In another form the lubricant comprising 0.1 to 60, preferably 0.1 to 40 wt % of the polyacrylate. The treat rate is usually adapted to the application of the lubricant. Typical treat rates are:

-   -   Automatic transmission fluid (ATF): 0.5-10 wt %     -   Manual transmission fluid (MTF): 0.5-10 wt %     -   Gear oil: 2-35 wt %     -   Hydraulic fluid: 1-25 wt %     -   Engine oil: 1-10 wt %.

The molecular weight M_(w) of the poly(meth)acrylate in the lubricant can be varied in broad ranges, such as from 1000-1,000,000 g/mol. The is usually adapted to the application of the lubricant. Typical molecular weights M_(w) are:

-   -   ATF: 10,000 to 400,000 g/mol, preferably 10,000 to 200,000 g/mol     -   MTF, CVTF: 5,000 to 200,000 g/mol, preferably 10,000 to 60,000         g/mol     -   Gear oil: 5,000 to 200,000g/mol, preferably 10,000 to 60,000         g/mol     -   Hydraulic fluid: 20,000 to 300,000 g/mol, preferably 30,000 to         180,000 g/mol     -   Engine oil: 50,000 to 1,000,000 g/mol, preferably 100,000 to         750,000 g/mol

The lubricant usually further comprises

-   a base oil selected from mineral oils, polyalphaolefins, polymerized     and interpolymerized olefins, alkyl naphthalenes, alkylene oxide     polymers, silicone oils, phosphate ester and carboxylic acid ester;     and/or -   a lubricant additive.

The base oil may be selected from the group consisting of mineral oils (Group I, II or III oils), polyalphaolefins (Group IV oils), polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate esters and carboxylic acid esters (Group V oils). Preferably, the base oil is selected from Group I, Group II, Group III base oils according to the definition of the API, or mixtures thereof. Definitions for the base oils are the same as those found in the American Petroleum Institute (API) publication “Engine Oil Licensing and Certification System”, Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998. Said publication categorizes base oils as follows:

a) Group I base oils contain less than 90 percent saturates (ASTM D 2007) and/or greater than 0.03 percent sulfur (ASTM D 2622) and have a viscosity index (ASTM D 2270) greater than or equal to 80 and less than 120.

b) Group II base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120.

c) Group III base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120.

d) Group IV base oils contain polyalphaolefins. Polyalphaolefins (PAO) include known PAO materials which typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include but are not limited to C2 to about C32 alphaolefins with the C8 to about C16 alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene, and poly-1-dodecene.

e) Group V base oils contain any base oils not described by Groups I to IV. Examples of Group V base oils include alkyl naphthalenes, alkylene oxide polymers, silicone oils, and phosphate esters.

Synthetic base oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); poly-phenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and derivative, analogs and homologs thereof.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic base oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having a molecular weight of 1000 or diphenyl ether of polyethylene glycol having a molecular weight of 1000 to 1500); and mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-C8 fatty acid esters and C13 oxo acid diester of tetraethylene glycol.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxysilicone oils and sili-cate oils comprise another useful class of synthetic base oils; such base oils include tetraethyl silicate, tetraisopropyl silicate, tetra-(2- ethylhexyl)silicate, tetra-(4-methyl-2-ethyl-hexyl) silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, poly(methyl) siloxanes and poly(methylphenyl)siloxanes. Other synthetic base oils include liquid esters of phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

Suitable lubricant additives may be selected from viscosity index improvers, polymeric thickeners, corrosion inhibitors, detergents, dispersants, anti-foam agents, dyes, wear protection additives, extreme pressure additives (EP additives), anti-wear additives (AW additives), friction modifiers, metal deactivators, pour point depressants.

The viscosity index improvers include high molecular weight polymers that increase the relative viscosity of an oil at high temperatures more than they do at low temperatures. Viscosity index improvers include polyacrylates, polymethacrylates, alkylmethacrylates, vinylpyrrolidone/meth-acrylate copolymers, poly vinylpyrrolidones, polybutenes, olefin copolymers such as an ethylene-propylene copolymer or a styrene-butadiene copolymer or polyalkene such as PIB, styrene/acrylate copolymers and polyethers, and combinations thereof. The most common VI improvers are methacrylate polymers and copolymers, acrylate polymers, olefin polymers and copolymers, and styrenebutadiene copolymers. Other examples of the viscosity index improver include polymethacrylate, polyisobutylene, alpha-olefin polymers, alpha-olefin copolymers (e.g., an ethylenepropylene copolymer), polyalkylstyrene, phenol condensates, naphthalene condensates, a styrenebutadiene copolymer and the like. Of these, polymethacrylate having a number average molecular weight of 10000 to 300000, and alpha-olefin polymers or alpha-olefin copolymers having a number average molecular weight of 1000 to 30000, particularly ethylene-alpha-olefin copolymers having a number average molecular weight of 1000 to 10000 are preferred. The viscosity index increasing agents can be added and used individually or in the form of mixtures, conveniently in an amount within the range of from ≥0.05 to ≥20.0% by weight, in relation to the weight of the base stock.

Suitable (polymeric) thickeners include, but are not limited to, polyisobutenes (PIB), oligomeric co-polymers (OCPs), polymethacrylates (PMAs), copolymers of styrene and butadiene, or high viscosity esters (complex esters).

Corrosion inhibitors may include various oxygen-, nitrogen-, sulfur-, and phosphorus-containing materials, and may include metal-containing compounds (salts, organometallics, etc.) and nonmetal-containing or ashless materials. Corrosion inhibitors may include, but are not limited to, additive types such as, for example, hydrocarbyl-, aryl-, alkyl-, arylalkyl-, and alkylaryl- versions of detergents (neutral, overbased), sulfonates, phenates, salicylates, alcoholates, carboxylates, salixarates, phosphites, phosphates, thiophosphates, amines, amine salts, amine phosphoric acid salts, amine sulfonic acid salts, alkoxylated amines, etheramines, polyetheramines, amides, imides, azoles, diazoles, triazoles, benzotriazoles, benzothiadoles, mercaptobenzothiazoles, tolyltriazoles (TTZ-type), heterocyclic amines, heterocyclic sulfides, thiazoles, thiadiazoles, mercaptothiadiazoles, dimercaptothiadiazoles (DMTD-type), imidazoles, benzimidazoles, dithiobenzimidazoles, imidazolines, oxazolines, Mannich reactions products, glycidyl ethers, anhydrides, carbamates, thiocarbamates, dithiocarbamates, polyglycols, etc., or mixtures thereof.

Detergents include cleaning agents that adhere to dirt particles, preventing them from attaching to critical surfaces. Detergents may also adhere to the metal surface itself to keep it clean and prevent corrosion from occurring. Detergents include calcium alkylsalicylates, calcium alkylphenates and calcium alkarylsulfonates with alternate metal ions used such as magnesium, barium, or sodium. Examples of the cleaning and dispersing agents which can be used include metal-based detergents such as the neutral and basic alkaline earth metal sulphonates, alkaline earth metal phenates and alkaline earth metal salicylates alkenylsuccinimide and alkenylsuccinimide esters and their borohydrides, phenates, salienius complex detergents and ashless dispersing agents which have been modified with sulphur compounds. These agents can be added and used individually or in the form of mixtures, conveniently in an amount within the range of from ≥0.01 to ≤1.0% by weight in relation to the weight of the base stock; these can also be high total base number (TBN), low TBN, or mixtures of high/low TBN.

Dispersants are lubricant additives that help to prevent sludge, varnish and other deposits from forming on critical surfaces. The dispersant may be a succinimide dispersant (for example N-substituted long chain alkenyl succinimides), a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbyl-amine dispersant, a polyether dispersant or a polyetheramine dispersant. In one embodiment, the succinimide dispersant includes a polyisobutylene-substituted succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000, or of about 950 to about 1600. In one embodiment, the dispersant includes a borated dispersant. Typically, the borated dispersant includes a succinimide dispersant including a polyisobutylene succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000. Borated dispersants are described in more detail above within the extreme pressure agent description.

Anti-foam agents may be selected from silicones, polyacrylates, and the like. The amount of anti-foam agent in the lubricant compositions described herein may range from ≥0.001 wt.-% to ≤0.1 wt.-% based on the total weight of the formulation. As a further example, an anti-foam agent may be present in an amount from about 0.004 wt.-% to about 0.008 wt.-%.

Suitable extreme pressure agent is a sulfur-containing compound. In one embodiment, the sulfur-containing compound may be a sulfurised olefin, a polysulfide, or mixtures thereof. Examples of the sulfurised olefin include a sulfurised olefin derived from propylene, isobutylene, pentene; an organic sulfide and/or polysulfide including benzyldisulfide; bis-(chlorobenzyl) disulfide; dibutyl tetrasulfide; di-tertiary butyl polysulfide; and sulfurised methyl ester of oleic acid, a sulfurised alkylphenol, a sulfurised dipentene, a sulfurised terpene, a sulfurised Diels-Alder adduct, an alkyl sulphenyl N′N-dialkyl dithiocarbamates; or mixtures thereof. In one embodiment, the sulfurised olefin includes a sulfurised olefin derived from propylene, isobutylene, pentene or mixtures thereof. In one embodiment the extreme pressure additive sulfur-containing compound includes a dimercaptothiadiazole or derivative, or mixtures thereof. Examples of the dimercaptothiadiazole include compounds such as 2,5-dimercapto-1,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof. The oligomers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically form by forming a sulfur-sulfur bond between 2,5-dimercapto-1,3,4-thiadiazole units to form derivatives or oligomers of two or more of said thiadiazole units. Suitable 2,5-dimercapto-1,3,4-thiadiazole derived compounds include for example 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-1,3,4-thiadiazole. The number of carbon atoms on the hydrocarbyl substituents of the hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically include 1 to 30, or 2 to 20, or 3 to 16. Extreme pressure additives include compounds containing boron and/or sulfur and/or phosphorus. The extreme pressure agent may be present in the lubricant compositions at 0 wt.-% to about 20 wt.-%, or at about 0.05 wt.-% to about 10.0 wt.-%, or at about 0.1 wt.-% to about 8 wt.-% of the lubricant composition.

Examples of anti-wear additives include organo borates, organo phosphites such as didodecyl phosphite, organic sulfur-containing compounds such as sulfurized sperm oil or sulfurized terpenes, zinc dialkyl dithiophosphates, zinc diaryl dithiophosphates, phosphosulfurized hydrocarbons and any combinations thereof.

Friction modifiers may include metal-containing compounds or materials as well as ashless compounds or materials, or mixtures thereof. Metal-containing friction modifiers include metal salts or metal-ligand complexes where the metals may include alkali, alkaline earth, or transition group metals. Such metal-containing friction modifiers may also have low-ash characteristics.

Transition metals may include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include hydrocarbyl derivative of alcohols, polyols, glycerols, partial ester glycerols, thiols, carboxylates, carbamates, thiocarbamates, dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides, imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and other polar molecular functional groups containing effective amounts of O, N, S, or P, individually or in combination. In particular, Mo-containing compounds can be particularly effective such as for example Mo-dithiocarbamates, Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am), Mo-alcoholates, Mo-alcohol-amides, and the like.

Ashless friction modifiers may also include lubricant materials that contain effective amounts of polar groups, for example, hydroxyl-containing hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives, and the like. Polar groups in friction modifiers may include hydrocarbyl groups containing effective amounts of O, N, S, or P, individually or in combination. Other friction modifiers that may be particularly effective include, for example, salts (both ash-containing and ashless derivatives) of fatty acids, fatty alcohols, fatty amides, fatty esters, hydroxyl-containing carboxylates, and comparable synthetic long-chain hydrocarbyl acids, alcohols, amides, esters, hydroxy carboxylates, and the like. In some instances, fatty organic acids, fatty amines, and sulfurized fatty acids may be used as suitable friction modifiers. Examples of friction modifiers include fatty acid esters and amides, organo molybdenum compounds, molybdenum dialkylthiocarbamates and molybdenum dialkyl dithiophosphates.

Suitable metal deactivators include benzotriazoles and derivatives thereof, for example 4- or 5-alkylbenzotriazoles (e.g. triazole) and derivatives thereof, 4,5,6,7-tetrahydrobenzotriazole and 5,5′-methylenebisbenzotriazole; Mannich bases of benzotriazole or triazole, e.g. 1-[bis(2-ethyl-hexyl) aminomethyl) triazole and 1-[bis(2-ethylhexyl) aminomethyl)benzotriazole; and alkoxy-alkylbenzotriazoles such as 1-(nonyloxymethyl)benzotriazole, 1-(1-butoxyethyl) benzotriazole and 1-(1-cyclohexyloxybutyl) triazole, and combinations thereof. Additional non-limiting examples of the one or more metal deactivators include 1,2,4-triazoles and derivatives thereof, for example 3-alkyl(or aryl)-1, 2,4-triazoles, and Mannich bases of 1,2,4-triazoles, such as 1-[bis(2-ethylhexyl)aminomethyl-1-1, 2,4-triazole; alkoxyalky1-1, 2,4-triazoles such as 1-(1-butoxyethyl)-1, 2,4-triazole; and acylated 3-amino-1, 2,4-triazoles, imidazole derivatives, for example 4,4′-methylenebis(2-undecyl-5-methylimidazole) and bis[(N-methyl)imidazol-2-yl]carbinol octyl ether, and combinations thereof. Further non-limiting examples of the one or more metal deactivators include sulfur-containing heterocyclic compounds, for example 2-mercaptobenzothiazole, 2,5-dimercapto-1, 3,4-thia-diazole and derivatives thereof; and 3,5-bis[di(2-ethylhexyl)aminomethyl]-1, 3,4-thiadiazolin-2-one, and combinations thereof. Even further non-limiting examples of the one or more metal deactivators include amino compounds, for example salicylidenepropylenediamine, salicylami-noguanidine and salts thereof, and combinations thereof. The one or more metal deactivators are not particularly limited in amount in the composition but are typically present in an amount of from about 0.01 to about 0.1, from about 0.05 to about 0.01, or from about 0.07 to about 0.1, wt.-% based on the weight of the composition. Alternatively, the one or more metal deactivators may be present in amounts of less than about 0.1, of less than about 0.7, or less than about 0.5, wt.-% based on the weight of the composition.

Pour point depressants (PPD) include polymethacrylates, alkylated naphthalene derivatives, and combinations thereof. Commonly used additives such as alkylaromatic polymers and polymethacrylates are also useful for this purpose. Typically, the treat rates range from 0.001 wt.-% to 1.0 wt.-%, in relation to the weight of the base stock.

Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof.

The lubricant can be prepared by contacting the polyacrylate and the base oil (e.g. selected from mineral oils, polyalphaolefins, polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate ester and carboxylic acid ester), and optionally the lubricant additive. The contacting can be achieved by mixing, stirring, pouring in the desired amounts.

The invention offers various advantages: the polyacrylate can be used in various lubricant applications (such as transmission, gear, hydraulic, engine oil, etc.) where low-temperature properties are critical.

EXAMPLES Example 1—Alcohol Preparation

A C_(13/15) alkanol was prepared according to WO 2002/00580. The obtained C_(13/15) alkanol was analyzed by GC. The average composition from several preparations was as follows:

30.9 wt % linear C₁₃ alkanol

37.6 wt % branched C₁₃ alkanol

13.1 wt % linear C₁₅ alkanol

17.9 wt % branched C₁₅ alkanol

The amount of C₁₂ alkanol, C₁₄ alkanol and C₁₆ alkanol was each below 1 wt %.

Example 2—Monomer Preparation

In a stirred 4 L reactor cyclohexan (1490 g), C_(13/15) alkanol from Example 1 (1935 g), hydroquinone monomethyl ether MeHQ (2,3 g), hypophosphoric acid 50% in water (5,8 g) and Cu(II) chloride solution (20% ig, 1,35 g) were added. Then methacrylic acid (968 g, stabilized with 200 ppm MeHQ), p-toluolsulfonic acid monohydrate (51,4 g) were added and heating started. At a sump temperature of 81 to 100° C. water went over. After 6,3 h the reaction was stopped. The reaction mixutre was cooled down and extraction with NaOH solution and with water. After phase separation 250 mg MeHQ were added to the organic phase and concenentrated in vacuum. 2451 g of methacrylic ester of the C_(13/15) alkanol were obtained with a purity of >98 GC-Fl%.

Example 3—Polymerization

66.7 g of the monomer from Example 2 and 1.8 g n-dodecyl-mercaptane (DDM) were mixed in a flask and heated up to 95° C. resulting in a colorless, clear solution. 25.33 g of a 9% solution of tert-butylperoctoate (TBPEH) in paraffinic oil was prepared and continuously fed within 2 hours. Separately, but parallel a mixture of 133.33 g of the C_(13/15) acrylate from Example 2 and 3.6 g n-dodecylmercaptane was fed continuously to the flask for 2 hours. The prepared polymer solution was then stirred without any further initiator feed at 95° C. for 60 min and at 130° C. for 30 min. The obtained 90% polymer solution is allowed to cool down to room temperature forming a colorless, viscous liquid.

Polymers were prepared varying amount of tert-butylperoctoate and dodecylmercaptane amount. The reaction temperature and solvent were kept constant.

The viscosity was determined (Brookfield, at 100° C.). The molecular weight Mw was determined by GPC analysis (polystyrene standard, detector: DRI Agilent 1100 UV Agilent 1100 VWD [254 nm]) with tetrahydrofuran+0.1% trifluoracetic acid eluent (flow rate: 1 ml/min) at a concentration of 2 mg/ml on a PLgel MIXED-B column.

TABLE 1a Polymer # TBPEH/g DDM/g KV100/cSt Mw/g/mol PDI 1 2.28 5.39 512 21 900 1.9 2 2.28 5.65 486 21 000 1.9 3 2.28 6.06 448 19 800 1.8 4 2.28 6.73 378 17 600 1.8

Comparative polymers were synthesized from the methacrylate monomers in Table 1b according to the above procedure and characterized as summarized in Table 1b. The following monomers were used:

TDN: Methacrylate based on Isotridecanol N from BASF SE which contained at least 99% of tridecanol isomers.

Lialchem 25/75: Methacrylate of Lialchem® 25/75 from Sasol, which contained an alkanol distribution of 22% C12, 32% C13, 29% C14, 17% C15 and 0.5% C16 or higher, and an overall content of linear alcohols of 77 wt %.

Neodol 25: Methacrylate of Neodol® 25 from Shell Chemicals, which contained an alkanol distribution of <1% C11 or lower, 21% C12, 29% C13, 25% C14, 25% C15 and <1% C16 or higher.

Lial 125: Methacrylate of Lial® 125 from Sasol, which contained an alkanol distribution of <1% of C11 and lower, 19-25% C12, 28-34% C13, 27-33% C14, 15-21% C15 and <1.5% C16 or higher, and an overall content of linear alcohols of 43 wt %.

TABLE 1b Comparative Polymers Polymer Methacrylate TBPEH/ DDM/ KV100/ Mw/ # of g g cSt g/mol PDI C1 TDN 2.28 5.39 1068 19 100 1.9 C2 Lialchem 5/75 3.60 6.73 298 17 700 1.9 C3 Lialchem 5/75 3.60 5.39 520 26 600 2.0 C4 Neodol 25 3.60 5.39 376 22 800 2.0 C5 Lial125 2.28 4.71 587 21 400 2.0 C6 Lial125 2.28 6.06 411 17 100 1.9

Example 4—Low Temperature Viscosity of Oil Blends

Oil blends were prepared with the following composition in Table 2. The treat rate of the polyacrylate is given in the Table 3. A group I base oil (KV 40 about 30 mm²/s, ASTM D445, pour point below −15° C., viscosity index >95) was added at the end to balance to 100%.

TABLE 2 Component Amount (wt. %) HiTEC ® 369 (gear oil additive package, Afton 6.00 Chemical) Irgaflo ® 649 P (pour point depressant, BASF 0.2 Corp.) SpectraSyn ® 4 (Polyalphaolefinn, group IV 15 base oil, ExxonMobil) Polyacrylate from Example 3 cf. Treat Rate Group I base oil (ExxonMobil) Balanced

The kinematic viscosity at 100° C. (“KV100”) was determined according to ASTM D445. The low temperature viscosity (“LTB at −40° C.”) was determined by rotational viscometer ASTM D2983 at −40° C. and the results are summarized in Table 3 and 4.

The data showed that the polyacrylates according to our invention have desirable lower viscosity at low temperatures compared to other polymers.

TABLE 3 Treat rate KV 100 LTB at −40° C. Blend # Polymer # [%] [cSt] [cSt] B1 1 26 16.6 94800 B2 2 26 16.0 97000 B3 2 27.5 17.0 110000 B4 3 27.5 16.7 104000 B5 4 26 14.6 85600 B6 4 27.5 15.5 97600

TABLE 4 Comparative Data Treat rate KV 100 LTB at −40° C. Blend # Polymer # [%] [cSt] [cSt] BC1 C1 22 14.5 522000 BC2 C1 24 16.0 2000000 BC3 C2 28.5 16.1 2000000 BC4 C3 23 16.4 2000000 BC5 C4 26 16.3 2000000 BC6 C5 25.5 16.7 123000 BC7 C5 26.5 17.4 132000 BC8 C6 26 14.9 111000 BC9 C6 27 15.5 115000

Example 5—Copolymers

The methacrylic ester of the C_(13/15) alkanol of example 2 was copolymerized with 10 wt % methyl methacrylate as follows.

70.0 g of the monomer from Example 2, 6.67 g methyl methacrylate and 2.16 g n-dodecyl-mercaptane in 72 g Nynas® T3 (low viscosity hydrotreated naphthenic API Group V base oil) were mixed in a flask and heated up to 95° C. resulting in a colorless, clear solution. 26 g of a 9% solution of tert-butylperoctoate in paraffinic oil was prepared and continuously fed within 2 hours. Separately, but parallel a mixture of 120 g of the C_(13/15) acrylate from Example 2, 13.3 g methyl methacrylate and 4.3 g n-dodecylmercaptane and 115 g of a 9% solution of tert-butylperoctoated was fed continuously to the flask for 2 hours. The prepared polymer solution was then stirred without any further initiator feed at 95° C. for 60 min and at 130° C. for 30 min. The obtained 60% polymer solution is allowed to cool down to room temperature forming a colorless, viscous liquid.

The polymers were analyzed as decribed in Example 3, and the results are summarized in Table 5.

TABLE 5 Polymer # TBPEH/g DDM/g KV100/cSt Mw/g/mol PDI 5 6.92 6.48 58 14 600 2.2 6 6.92 8.10 42 12 100 2.1 7 6.92 4.06 66 17 600 2.3

Example 6—Low Temperature Viscosity of Oil Blends

Oil blends were prepared with the following composition in Table 6 with the polyacrylate from Example 3. The treat rate of the polyacrylate is given in the Table 7.

TABLE 6 Oil blends with given SAE J 306 viscosity grades, amount in wt. % B7 B8 B9 Component 75W-80 75W-85 80W-140 HiTEC ® 369 (gear oil additive package, 6.0 6.0  6.0 Afton Chemical) Irgaflo ® 649 P (pour point depressant, 0.5 0.5 — BASF Corp.) Chevron Neutral Oil 220R (Group II — — 30.9 parrafinic base oil, KV40 41 cSt, VI 102) Chevron Neutral Oil 600R (Group II — — 32.4 parrafinic base oil, KV40 106 cSt, VI 102) Yubase 4 (Group III base oil, KV40 19.6 21.0 17.5 — cSt, VI 122) Yubase 6 (Group III base oil, KV40 36.8 60.0 57.4 — cSt, VI 131)

The oil blends were tested as described in Example 4 and the results are summarized in Table 7.

TABLE 7 Treat LTB Blend Polymer rate KV 100 at −40° C. # SAE # [%] [cSt] [cSt] B7 75W-80 2 12.5 13.07 75000 B8 75W-85 2 18.6 10.00 51000 B9 80W-140 2 30.7 29.80 120000 

1.-15. (canceled)
 16. A lubricant comprising a polyacrylate which contains a C_(13/15) acrylate in polymerized form, where the C_(13/15) acrylate comprises at least 70 wt % of linear and branched C₁₃ and C₁₅ alkyl (meth)acrylates.
 17. The lubricant according to claim 16 where the linear and branched C₁₃ and C₁₅ alkyl groups of the C_(13/15) acrylate are derived from a C_(13/15) alkanol obtained by reacting a monoolefin mixture of C₁₂ and C₁₄ olefins with carbon monoxide and hydrogen.
 18. The lubricant according to claim 16 where the C_(13/15) acrylate comprises less than 5 wt % of each C₁₂, C₁₄ and C₁₆ alkyl (meth)acrylate.
 19. The lubricant according to claim 16 where the C_(13/15) acrylate comprises a weight ratio of branched C₁₃ and C₁₅ alkyl to linear C₁₃ and C₁₅ alkyl in a range from 3:1 to 1:3.
 20. The lubricant according to claim 16 where the C_(13/15) acrylate comprises at least 40 wt % of branched C₁₃ and C₁₅ alkyl groups.
 21. The lubricant according to claim 16 where the C_(13/15) acrylate comprises 35 to 85 wt % of linear and branched C₁₃ alkyl groups.
 22. The lubricant according to claim 16 where the C_(13/15) acrylate comprises 15 to 50 wt % of branched C₁₃ alkyl groups.
 23. The lubricant according to claim 16 where the C_(13/15) acrylate comprises 20 to 60 wt % of linear C₁₃ alkyl groups, 10 to 50 wt % of branched C₁₃ alkyl groups, 3 to 30 wt % of linear C₁₅ alkyl groups, and 3 to 30 wt % of branched C₁₅ alkyl groups.
 24. The lubricant according to claim 16 where the polyacrylate comprises at least 50 wt % of the C_(13/15) acrylate.
 25. The lubricant according to claim 16 where the polyacrylate comprises up to 25 wt % of a comonomer selected from C₁-C₁₈ alkyl (meth)acrylate.
 26. The lubricant according to claim 16 comprising 0.1 to 40 wt % of the polyacrylate.
 27. A polyacrylate as defined in claim
 16. 28. A C_(13/15) acrylate as defined in claim
 16. 29. A method for preparing the polyacrylate as defined in claim 16 by free-radical polymerization of the C_(13/15) acrylate as defined in claim
 16. 30. A method for preparing a lubricant by contacting the polyacrylate as defined in claim 16 to a base oil. 